When you are using /dev/random to generate OpenPGP public/private key pairs or other key materials for long-term, you might run into the common problems of lacking entropy in the pool. So you have to wait until enough entropy is gather on the system to continue the key generation. Especially gathering entropy on system might be difficult or even introduces some issues when the system is used by multiple users (http://www.pinkas.net/PAPERS/gpr06.pdf).